Patents must satisfy legal tests

Patents for software inventions have existed in Europe for years, and the legal requirements are no different than the requirements for patenting advances in other technologies.

Software patents do not "restrict" computer users; they will not "tie up" software developers; the European consumer will not be harmed. The US has allowed software patents even longer than Europe. It is easier to file infringement suits in the US, and hard for victorious defendants to force losing plaintiffs to pay their legal bills: nevertheless, the US software industry leads the world.

Critics tend to omit the precise features of patent law that defeat their arguments. The world's patent laws do not protect "mundane" advancements in any field. A patentable invention must satisfy the legal tests of novelty, inventive step and industrial applicability.

A patent examiner - an impartial governmental official - reviews pending patent applications, and even if the examiner allows the patent, it will only last a limited time.

We are supposedly entering a "knowledge economy", and intellectual property law represents the collective body of laws for protecting knowledge. Exempting software would create an odd economic and legal aberration whose full effects could not be easily determined.

The appeal of the patent system is fairly clear: assume you invent the software controls that enable low-cost, zero-emission engines. With a patent system, you may be compensated for your labours. Without a patent system, your compensation depends upon the ability to exploit the invention against competitors who may have enormous intrinsic advantages over you.

No one suggests waiving the novelty and inventive step requirements for any patentable technology. So, the only issue is whether software has industrial utility. If it does, for example in software for avionics, power station controls and life support monitors, then patenting could not be more appropriate.

Much of the critique of software patents arises in the open source movement, which proposes that software be monetised (if at all) by the sale of professional services. But no business model should be forced upon every company in any industry.

Europe has slim prospects for becoming a paradise for junk patents, software or otherwise. Among other things, patents can be opposed and invalidated. But if Europe is to ban software patents, then it should do so for the right reasons.

· If you'd like to comment on any aspect of Online, send your emails to online.feedback@theguardian.com.Please include your address and telephone number. If you do not want your email address published, please say so.